Electrical wire cutting apparatus

ABSTRACT

A wire cutting apparatus is provided having a pair of spaced apart, highly electrically conductive electrodes such as tungsten or platinum, and an insulated bias means for urging the wire to be cut against the electrodes. A power source applies a low voltage, high power electrical signal between the electrodes preferably of between 1.5 and 5 volts and of at least 25 amperes. On insertion of a stranded wire or the like between the bias means and electrodes, a high current flows through portions of the wire between the electrodes to generate localized heat to melt and cut the wire while welding the ends of the stranded wire.

United States Patent [1 1 Lauer 1 1 ELECTRICAL WIRE CUTTING APPARATUS [75] Inventor: Cornelius Lauer, Stow, Ohio [73] Assignee: The General Tire & Rubber Company, Akron, Ohio 22 Filed: Feb. 17, 1972 211 App]. No.: 227,064

[52] US. Cl. 219/68 June 19, 1973 1,059,390 4/1913 Pierce 219/86 Primary Examiner-R. F. Staubly [57] ABSTRACT A wire cutting apparatus is provided having a pair of spaced apart, highly electrically conductive electrodes such as tungsten or platinum, and an insulated bias means for urging the wire to be cut against the electrodes. A power source applies a low voltage, high power electrical signal between the electrodes preferably of between 1.5 and 5 volts and of at least 25 amperes. On insertion of a stranded wire or the like between the bias means and electrodes, a high current flows through portions of the wire between the electrodes to generate localized heat to melt and cut the wire while welding the ends of the stranded wire.

3 Claims, 2 Drawing Figures ELECTRICAL WIRE CUTTING APPARATUS FIELD OF THE INVENTION This invention relates to cutting apparatus and particularly apparatus for cutting stranded wire by electrical heating.

BACKGROUND OF THE INVENTION Various apparatus has been proposed for cutting wire and the like. The most common means is a pliers or the like which mechanically slices through the wire. Such devices are very successful with small gage wire of solid cross-sections; however, such devices present difficulties in cutting heavy gage wire and stranded wire. Heavy gage wire requires that the device possess a large mechanical advantage or be motor driven to enable cutting to be accomplished. But such devices are themselves heavy and complex which in turn makes them expensive and cumbersome to handle.

Moreover, such devices present difficulties in cutting stranded wire. The cutting of stranded wire with such devices allows the wire ends free to untwist. It is therefore common to manually twist or tape the ends after cutting to provide for further use. But such added procedures are time consuming and do not always keep the stranded ends from balling, which requires that the ends be recut to enable the wires to be used.

The present invention overcomes these difficulties and disadvantages. It provides an inexpensive and uncomplicated means for cutting wire of all sizes rapidly and particularly stranded wire without untwisting of the ends.

SUMMARY OF THE INVENTION A wire cutting apparatus comprises at least a pair of spaced apart electrodes of high electrical conductivity such as tungsten or platinum. The electrodes are rigidly supported by support means in electrically insulated, spaced apart relation and are connected by connecting wires or other means to a power source. The power source thereby applies a low voltage, high power electrical signal between the electrodes.

An electrically and thermally insulated bias means is provided for urging a wire to be put into contact with said electrodes. Preferably the bias means is connected to a foot pedal to open the bias means so that a wire can be easily inserted into the apparatus for cutting.

In operation, the apparatus is portably mounted on the edge of a table or the like and the foot pedal positioned so that it can be activated. A stranded wire or the like is positioned between the electrodes and the bias means. An electrical circuit is thereby formed across the electrodes causing a low voltage, preferably between l.5 and 5 volts, and heavy current at least above 25 amperes and preferably above 50 amperes to electrically flow through the localized portion of the wire between the electrodes. Since the wire has a low electrical conductivity (i.e. high electrical resistance), the wire is rapidly heated to a temperature causing it to melt and easily separate. At thesame time, the ends of the strands of wire are welded together so that they cannot untwist.

Other details, objects and advantages of the invention will become apparent as the following description of a present preferred embodiment and a present preferred method of practicing the same proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, the present preferred embodiment of the invention and the present preferred method of practicing the invention is illustrated in which:

FIG. 1 is an elevation view of an electrical cutting apparatus attached to an edge of a table or the like; and

FIG. 2 is a side view in elevation of the electrical cutting apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an electrical cutting apparatus is provided having a pair of electrodes of high electrical conductivity. Suitable material for the electrodes are tungsten and platinum. Preferably tungsten is used for electrodes 10 because tungsten electrodes are readily available in the form of welding rods. Moreover, tungsten electrodes prevent melted wire from sticking to them; and unlike carbon electrodes, there is little oxidation or wear on tungsten. Each electrode 10 is separately supported by a terminal block 11 and is rigidly fastened to terminal block 11 by clamp 12 and threaded cap screw 13. Each cap screw '13 is threaded into an opening 14 in terminal block 11.

Each terminal block 11 is separately connected to lead wire 15 by connector 16 positioned in opening 17 and rigidly fastened to terminal block 11 by threaded cap screw 18 threaded into opening 19 to engage connector 16. Lead wires 15 are in turn connected to a low voltage, high power electrical source (not shown). By

this arrangement, a low voltage, high power electrical signal is applied between the electrodes 10.

Electrodes 10 are spaced apart by positioning terminal blocks 11 in relation to base 20. Each terminal block 11 is rigidly fastened to base 20 by threading cap screw 21 into opening 22 in base 20 and corresponding opening 23 in terminal block 11. The terminal blocks 1 l are electrically insulated from each other by insulating spacer 24 between the terminal blocks 11. The spacing of electrodes 10 will vary depending on the size of the wire to be cut and the size of the power supply. Preferably, the spacing between electrodes 10 ranges from one thirty-second to one-eighth inch.

Bias means 25 are provided for urging a wire to be out against electrodes 10. Bias means 25 has pressure pin 26 with head 27 covered with ceramic insulation pad 28. To assemble bias means 25, spring 29 is positioned over pin 26, and pin 26 is thereafter inserted through opening 30 in base 20. Pin 26 is positioned with spring 29 under compression by fitting set collar 31 over pin 26 against the bottom surface of base 20, and threading set screw 32 through collar 31 to engage pin 26.

Preferably bias means 25 is connected to a foot pedal to open the bias means to readily insert a wire between electrodes 10 and bias means 25. Hog ring 33 is fastened into opening 34 in pressure pin 26. Hog ring 33 is connected to chain 35, and chain 35 is in turn connected through hog ring 36 and turnbuckle bolt 37 to foot pedal 38. For operation, the length of chain 35 and turnbuckle bolt 37 are adjusted so that the foot pedal 38 is just above the floor line. To open bias means 25 the foot pedal 38 is simply stepped on by the operator; and to close bias means 25 the foot pedal 38 is released by the operator.

To portably fasten the cutting apparatus, C-clamp assemblies 39 are fastened to base 20 by cap screw 40 threaded into opening 41 in base 20 and corresponding opening 42 in each C-clamp assembly 39. The cutting apparatus is thereby fastened to table 43 by tightening C-clamp assemblies 39 against the edge of table 43.

The operator is protected during operation of the cutting apparatus from sparks and the like by transparent shield 45. Brackets 44 are fastened to base 20 by cap screws 40 through openings corresponding to openings 41 in base 20. Transparent shield 45 is then fastened to brackets 44 by fastening means 46.

In operation of the cutting apparatus, bias means 25 is opened and a stranded wire or the like inserted. Bias means 25 is then released to urge the wire against the electrodes and close the electrical circuit with a power source through lead wires 15. A high current of at least about 25 amperes and preferably above 50 amperes (typically up to about 700 amperes) in turn flows through the portion of the wire between the electrodes. Since the wire has high electrical resistance, heat is generated in the wire causing it to melt. The heat generated is localized only in the wire because of the high electrical conductivity of the electrodes and low thermal and electrical conductivity of the ceramic insulation pad 28 of bias means 25. The heavy current flowing through the wire therefore melts and cuts it while simultaneously welding the cut ends of the wire so that the strands cannot untwist and ball.

By use of such apparatus, stranded cable of up to one-eighth inch in diameter has been readily cut without difficulty while protecting the newly cut ends against untwisting. Furthermore, the apparatus has been operated continuously without the danger of electrical shock or burns.

While the presently preferred embodiments of the invention have been specifically described, it is distinctly understood that the invention may be otherwise variously embodied and used within the scope of the following claims.

What is claimed is:

1. An apparatus for cutting twisted, stranded wire and simultaneously welding each cut end such that the cut ends will not untwist, said apparatus comprising:

A. a pair of spaced apart electrodes of high electrical conductivity;

B. an electrical circuit including a power source operatively associated with said pair of electrodes and adapted to apply a current above 25 amperes and a voltage between about 1.5 to 5 volts between said electrodes when contacted with a wire;

C. means for urging a stranded wire against said pair of electrodes said biased means comprising:

1. an insulated head for supporting a wire;

2. a spring biasing said head toward said electrodes;

3. a footpedal connected to said spring such that the spring bias on said head may be overcome to move said head away from said electrodes.

2. A wire cutting apparatus as set forth in claim 1 wherein the electrodes are selected from the group consisting of tungsten and platinum.

3. A wire cutting apparatus as set forth in claim 1 wherein more than 50 amperes of current is supplied to the electrodes upon contact with a wire. 

1. An apparatus for cutting twisted, stranded wire and simultaneously welding each cut end such that the cut ends will not untwist, said apparatus comprising: A. a pair of spaced apart electrodes of high electrical conductivity; B. an electrical circuit including a power source operatively associated with said pair of electrodes and adapted to apply a current above 25 amperes and a voltage between about 1.5 to 5 volts between said electrodes when contacted with a wire; C. means for urging a stranded wire against said pair of electrodes said biased means comprising:
 1. an insulated head for supporting a wire;
 2. a spring biasing said head toward said electrodes;
 3. a footpedal connected to said spring such that the spring bias on said head may be overcome to move said head away from said electrodes.
 2. a spring biasing said head toward said electrodes;
 2. A wire cutting apparatus as set forth in claim 1 wherein the electrodes are selected from the group consisting of tungsten and platinum.
 3. A wire cutting apparatus as set forth in claim 1 wherein more than 50 amperes of current is supplied to the electrodes upon contact with a wire.
 3. a footpedal connected to said spring such that the spring bias on said head may be overcome to move said head away from said electrodes. 